TORONTO -- One of two Ontario sisters who drowned their alcoholic mother when they were teenagers and almost got away with it has made an unlikely transition from murder to law school, a new film reveals.

The sordid tale of the so-called Bathtub Girls -- who were convicted of first-degree murder in the 2003 death of their mother in Mississauga, Ont. -- is now the subject of the movie "Perfect Sisters."

The film, opening Friday in select theatres across North America, including Toronto, notes that both girls are now in university -- one of them in law school -- but instead focuses on what led two young girls to murder their mother.

Filmed in Winnipeg, the movie stars Abigail Breslin, known for "Little Miss Sunshine" and Georgie Henley, known for "The Chronicles of Narnia" series. It's based on the book by former Toronto Star reporter Bob Mitchell, "The Class Project: How to Kill a Mother: The True Story of Canada's Infamous Bathtub Girls."

The movie, however, takes a markedly different perspective than the book.

Director Stan Brooks says he was determined for the story to be as accurate as possible to the real events and fictionalized almost nothing. But the story is portrayed through a far more sympathetic lens than Mitchell's book.

"It wasn't so simple as to say, 'These were sociopathic girls. They were just evil,"' Brooks said in an interview.

"I see how teens can make bad decisions in bad situations. I, as a parent myself, I'm much more cognizant of what might have taken place that got them there, without condoning what they did."

It was a very fine line to walk, between making the girls immediately unsympathetic and trying to understand their motives, Brooks said. The film focuses on their unstable lives with their alcoholic mother and her abusive boyfriend.

"It was not unintentional to cast two girls who have spent their careers being good girls on film so that the immediate audience reaction to seeing the girl from 'Little Miss Sunshine' and the darling from the 'Narnia' movies would be to like them," Brooks said.

"So it was a longer journey for the audience to take to watch them go bad, I think, than if I had cast two girls who had played villains before."

Mitchell, who covered the story extensively as a reporter, says he understands movie audiences need someone to root for, but he does not see the girls as sympathetic figures.

"If you didn't know the whole story, the movie comes across as these poor girls, basically, who were pushed to the limit and this is how they figured out how to get out of it, but then in the end they get caught," Mitchell said in an interview.

"I don't think the movie dealt with how cold-blooded and calculating they were."

The main reason for the murder was their mother's insurance policy, Mitchell said. He recalled the day in court when autopsy photos were displayed and the sisters were giggling.

Much more planning went into the murder than the film shows, Mitchell said. And one of the girls' biggest concerns in the immediate aftermath was that they wouldn't be able to party for a few weeks because they had to seem sad, he said.

When they were 15 and 16 years old the sisters staged the drowning, plying their alcoholic mother with drinks and feeding her Tylenol 3's before drawing her a bath.

Once in the bathtub, the older sister held the woman's head under water for some four minutes. They nearly got away with murder.

Their ploy to make their mother's death look like an accident worked for about a year, despite bragging about it to friends, until a family friend went to police.

They were sentenced to the maximum allowed for kids their age who commit first-degree murder: 10 years, some of that behind bars, the rest under conditions in the community. Their sentences will expire completely next year.

The girls' real names were put under a publication ban because they were under 18 when they killed their mother, so the characters in the movie were given fake names.

The older sister is still using her real name, which has appeared in newspapers when the girl won awards, Mitchell said. The younger sister is in law school, he said.

"All their fellow students would have absolutely no idea who they are unless they told them," Mitchell said.

Brooks, a U.S.-born permanent resident of Canada, is deeply curious to know what the sisters think of his portrayal of them.

"Because the movie is opening April 11 in Toronto and I'm coming up, I do think about getting that tap on the shoulder: 'Hi, I wanted to meet you. I'm the girl that you called Elizabeth,"' Brooks said from San Diego. Calif.

"I hope they go see the movie. I think I treat them pretty fairly -- probably more fair than the book did."